Treaty Regulating Immigration from China 1880 (also at Wikisource; at Wikipedia), known commonly as the "Angell Treaty" after its primary US negotiator James B. Angell, which amended the 1868 Burlingame-Seward Treaty (in this same document at US Library of Congress; at Wikisource; at Wikipedia).

1868 Burlingame-Seward Treaty (at Wikisource; at Wikipedia).